General comment

Omaha-Ponca may show the unextended root, though all of DH is problematic
because post-accentual *p is generally retained. Dakotan -e- is
unexplained, though note the correlation of e with x and o with ɣ.

Lakotaɣ is not explained since x > ɣ only postonically. DH probably has
ɣ, mistranscribed as x by most workers because, unlike the other
pairs of fricatives, this one does not involve voicing. DH has a different
root extension. Ofo seems to show the same two vowels that we find in Lakota.

s and š apparently do not contrast in Ofo, and both are reflexes of Proto-Siouanx.